面试题---求一个串中的最大连续递增数字串

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

void max(char *str)
{
    char *p = str;
    int max_len = 0;
    char *max_start = NULL;
    while(*p != '')
    {

        if(*p >= '0' && *p <= '9')
        {
            int len = 1;
            char *q = p;
            while((*q != '') && (*q >= '0' && *q <= '9') && (*(q + 1) == *q + 1))
            {
                len++;
                q++;
            }
            if(len > max_len)
            {
                max_len = len;
                max_start = p;
            }
            p = q + 1;
        }
        p++;
    }
    if(max_start != NULL)
    {
        fwrite(max_start,max_len,1,stdout);
        printf("
");
    }
}
int main()
{
    printf("输入第一个字符串：
");
    char str[256];
    scanf("%s",str);
    printf("%s
",str);
    max(str);
    return 0;
}